This is a 48 week, open-label, randomized, multicenter, efficacy, and safety study. A total of 300 patients will be randomly allocated to one of two treatment regimens ( 100 in Treat A and 200 in Treatment B,1:2 ratio): :Continued therapy with current PI(s)+ two NRTIs or two PIs + two NTRI regimen (treatment A) :Efavirenz (600 mg orally QD)+continued therapy with two NRTIs (Treatment B)-see glossary for abbreviation The PI(s) and NTRI medication will not be supplied by sponsor for Treatment A, the NTRI and PI(s) will remain the same as those administered prior to study entry and will be the patient's first effective HIV protease Inhibitor-containing regimen. For Treatment B, patients randomized to efavirenz.